RIVERTON - Fremont County authorities presume that a man missing since Sunday drowned in Boysen Reservoir north of Shoshoni.

Authorities identified the man Tuesday as Michael Lee Peck-Jacobs, 29, of Lander.

Rescue teams searched the waters from Sunday night to Monday afternoon. The presumed victim was thrown overboard from a pontoon house boat when wind gusts of 30 mph created 8- to 9-foot waves. He was not wearing a life jacket.

Fremont County Sheriff's Capt. Roger Millward said another man was thrown from the craft but was rescued by another boater. He was identified as Rhet Foster, 24, of Hudson.

Four others were on the pontoon. Millward said they managed to hang onto the craft as it nearly rolled over before coming to rest on its side, on one of the pontoons. They then climbed to the high side and tipped the boat upright.

No charges are expected to be filed against the boat's operator, Nicholas Knollenberg, 19, of Riverton. Others on the boat were drinking alcohol, but authorities say Knollenberg was not and no boating regulations were violated.

Millward said the wind picked up and stalled the boat's motor as the group was heading back to the marina from the center of the reservoir. Boysen is about 4 to 5 miles wide. The boat was piloted to shore under its own power after someone from the marina came out and repaired it.

Authorities said there were enough life jackets onboard for all boaters, but none of them were being worn when the boat tipped. The boaters told authorities they had just moved to the deck compartment to retrieve the life vests when the wave hit the pontoon. The four boaters who stayed aboard managed to put their life jackets on after the incident.

"It was a nice, sunshiny, calm day when the storm front moved in rapidly," Millward said.

He cautioned that people who are boating, especially at Boysen Reservoir, need to stay attuned to the weather.

The incident happened just after 8 p.m. Sunday. County search and rescue teams were on site immediately and worked through the night, with a break in the early morning hours Monday. But Millward said visibility was poor because the water was deep and murky and dense foliage made the shorelines difficult to reach by boat or jet ski. Even an air search turned up nothing.

By Monday afternoon, searchers were running sonar cameras in the area where the missing man was last seen, and divers were on standby. The rescue operation moved into recovery mode by Tuesday afternoon and was continuing with air and boat searches.

Leslie Stratmoen is KVOW/KTAK news director in Riverton.